Development of novel total intravenous anesthesia protocol

Small ruminants are playing a vital role in the socio-economic wellbeing of people in developing countries, including Pakistan. Due to hike in prices of animals and animal products, owners want to get their animals treated surgically where surgical intervention is required. Surgical management always necessitates an ideal anesthetic to facilitate well-being of the surgical patient, but goats have been found more sensitive to anesthetic treatment as compared to other species. So, the most suitable anesthetic drug combination should be adopted to ensure minimal stress and its rapid clearance from body.

Traditionally, injectable anesthetic agents are only used as induction agents while inhalant agents are preferred to maintain anesthesia during more invasive procedures.

However, inhalation anaesthesia is not only associated with increased atmospheric contamination and occupation health risks to medical personnel but also very difficult to manage under field conditions. Therefore, intravenous anesthesia is the only option to maintain general anesthesia under field conditions. It needs only intravenous anesthetic agents and conventional syringe to maintain sufficient depth of anaesthesia as compared to inhalation anaesthesia.

Generally, two techniques are preferred for administering the intravenous anesthetic agents: multiple bolus technique and continuous infusion technique. The constant rate infusion technique has been found better and safer than the repeat bolus technique because it provided a continuous steady-state concentration of the drug, resulting in a more stable plan of anesthesia.

Keeping in view the new advancement in pharmacokinetic and pharmacodynamics properties of modern drugs, its sophisticated delivery systems and safety margin in different species, a research study was planned at UVAS to develop a suitable total intravenous anesthesia protocol by administering detomidine, midazolam, propofol and ketamine alone and in combination using constant rate infusion in goats during pain management. Different combinations of these drugs were made. Based on the findings of the study, the combination of detomidine-midazolam-propofol-ketamine was proved to be the best drug combination taking into account the sedative, dose sparing, anesthetic, clinico-physiological and haematobiochemical parameters. This combination was found safe, economical and reliable total intravenous anesthesia (TIVA) protocol. It will definitely help veterinarians to maintain surgical anaesthesia for prolonged periods during field surgeries without using bulky, expensive gas anesthesia machine. —-Muhammad Asif & Dr Muhammad Arif Khan